In recent years, PTT services are becoming popular, which realize one-to-many calls among mobile terminals having a PTT function. PTT services allow for a call among multiple people, however, do not allow two or more people to speak at the same time. Therefore, a user of a mobile terminal needs to wait for another user to finish speaking, and then acquire the right to speak before starting speaking.
A mobile telephone disclosed in Patent Literature 1 has a PTT function, and has a button used for making a PTT call (hereinafter “PTT button”). Specifically, when the PTT button is pressed, the mobile telephone acquires the right to speak from a PTT management server. The mobile telephone is maintained in voice transmission mode as long as the PTT button is being pressed, during which a voice can be transmitted.